P0651 GMC -

Question

I recently replaced both knock sensors on my 2004 GMC Sierra 1500, could I have done something to cause me now to have a check engine light on with the code p0651? The truck ran good for a week with no check engine lght.

Answer 1

Hi there,

This code indicates an issue with the ECM. Here is some info for you.

P0651 GMC - 5 Volt Sensor Reference 2 Circuit

Read more: https://www.autocodes.com/p0651_gmc.html